nictitating membrane

American  

[nik-ti-tey-ting mem-breyn] / ˈnɪk tɪˌteɪ tɪŋ ˈmɛm breɪn /

noun

1. a thin membrane, or inner or third eyelid, present in many animals, capable of being drawn across the eyeball, as for protection.

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nictitating membrane British  

/ ˈnɪktɪˌteɪtɪŋ /

noun

1. Also called: third eyelid.   haw.  (in reptiles, birds, and some mammals) a thin fold of skin beneath the eyelid that can be drawn across the eye

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nictitating membrane Scientific  

/ nĭk′tĭ-tā′tĭng /

1. A transparent inner eyelid in birds, reptiles, amphibians, and some mammals that protects and moistens the eye without blocking vision.

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Etymology

Origin of nictitating membrane

1705–15; nictitate ( def. ) + -ing ²

Example Sentences

Separately, the sclera, the eye’s outer layer, would most closely resemble those of horses and cows and include a nictitating membrane, the built-in goggles that make it possible to see underwater.

From New York Times

In her 2018 special “Elder Millennial,” she references a nictitating membrane, the translucent inner eyelid typically found in reptiles and birds.

From Los Angeles Times

A thin nictitating membrane covers their eyes to protect against sandstorms, and bushy eyebrows and a double row of extra-long lashes help to keep sand out.

From National Geographic

A cat has upper and lower eyelids that meet when the eye closes, along with a mysterious third eyelid—more properly called the palpebra tertia, also known as the nictitating membrane or “haw.”

From Scientific American

A nictitating membrane lowered itself over her eyes.

From Literature